Nitrogen excretion in rats on a protein-free diet and during starvation

Abstract

Nitrogen balances (six days) were determined in male Wistar rats during feeding a diet with sufficient protein or a nearly protein-free diet (n = 2 x 24), and then during three days of starvation (n = 2 x 12). The objective was to evaluate the effect of protein withdrawal on minimum nitrogen excretion in urine (UN), corresponding to endogenous UN, during feeding and subsequent starvation periods. The rats fed the protein free-diet had almost the same excretion of urinary N during feeding and starvation (165 and 157 mg/kg W(0.75)), while it was 444 mg/kg W(0.75) in rats previously fed with protein, demonstrating a major influence of protein content in a diet on N excretion during starvation. Consequently, the impact of former protein supply on N losses during starvation ought to be considered when evaluating minimum N requirement necessary to sustain life.

Anticatabolic activity of alpha-ketoglutaric acid in growing rats

“…Both the urinary and faecal endogenous fractions represent N, which has been already adsorbed and utilized by the animal. The amount of endogenous N varies depending on animal species, age, live weight, protein content of the diet before PFD and the so-called labile protein reserves (Chawalibog et al, 2008).…”